It sounds to me like you're trying to write map searching software and you've noticed that the Travelling Salesman Problem when applied in the real world also has to account for one-way roads. You are looking to solve this by representing the problem space as a Directed Graph?

Rather than mutating the data structure to have different distances in either direction, why not redefine the linking structure to support one-way connections? Wouldn't this allow the current path-searching/choosing routines to continue to be used without modification?

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other